Update build.sbt
Update build.sbt

make multisets dependency scala-portable
snithish/spark-testing-base,holdenk/spark-testing-base,holdenk/spark-testing-base,snithish/spark-testing-base,mahmoudhanafy/spark-testing-base,mahmoudhanafy/spark-testing-base,mahmoudhanafy/spark-testing-base,snithish/spark-testing-base,holdenk/spark-testing-base,snithish/spark-testing-base,mahmoudhanafy/spark-testing-base,holdenk/spark-testing-base